Semi

The Tesla Semi will deliver a far better experience for truck drivers, while increasing safety and significantly reducing the cost of cargo transport.

Unrivaled Performance

Without a trailer, the Tesla Semi achieves 0-60 mph in five seconds, compared to 15 seconds in a comparable diesel truck. It does 0-60 mph in 20 seconds with a full 80,000-pound load, a task that takes a diesel truck about a minute. Most notably for truck drivers and other travelers on the road, it climbs 5% grades at a steady 65 mph, whereas a diesel truck maxes out at 45 mph on a 5% grade. The Tesla Semi requires no shifting or clutching for smooth acceleration and deceleration, and its regenerative braking recovers 98% of kinetic energy to the battery, giving it a basically infinite brake life. Overall, the Semi is more responsive, covers more miles than a diesel truck in the same amount of time, and more safely integrates with passenger car traffic.

Driver Experience

Unlike other trucks, the Semi’s cabin is designed specifically around the driver, featuring unobstructed stairs for easier entry and exit, full standing room inside, and a centered driver position for optimal visibility. Two touchscreen displays positioned symmetrically on both sides of the driver provide easy access to navigation, blind spot monitoring and electronic data logging. Built-in connectivity integrates directly with a fleet’s management system to support routing and scheduling, and remote monitoring. Diesel trucks today currently require several third party devices for similar functionality.

Megachargers, a new high-speed DC charging solution, will add about 400 miles in 30 minutes and can be installed at origin or destination points and along heavily trafficked routes, enabling recharging during loading, unloading, and driver breaks.

Safety

The Tesla Semi’s all-electric architecture is designed to have a higher safety standard than any other heavy-duty truck on the market, with a reinforced battery that shields the Semi from impact and gives it an exceptionally low center of gravity. Its windshield is made of impact resistant glass. Jackknifing is prevented due to the Semi’s onboard sensors that detect instability and react with positive or negative torque to each wheel while independently actuating all brakes. The surround cameras aid object detection and minimize blind spots, automatically alerting the driver to safety hazards and obstacles. With Enhanced Autopilot, the Tesla Semi features Automatic Emergency Braking, Automatic Lane Keeping, Lane Departure Warning, and event recording.

Tesla Semi can also travel in a convoy, where one or several Semi trucks will be able to autonomously follow a lead Semi.

Reliability

With far fewer moving parts than a diesel truck – no engine, transmission, after-treatment system or differentials to upkeep – the Tesla Semi requires significantly less maintenance. Its battery is similar in composition to the batteries of Tesla energy products and is designed to support repeated charging cycles for over a million miles, while its motors are derived from the motors used in Model 3 and have been validated to last more than one million miles under the most demanding conditions.

Lowest Cost of Ownership

The biggest immediate cost-advantage comes from savings in energy costs: fully loaded, the Tesla Semi consumes less than two kilowatt-hours of energy per mile and is capable of 500 miles of range at GVW and highway speed, accommodating a wide range of shipping applications given that nearly 80% of freight in the U.S. is moved less than 250 miles. Coupled with the low and stable nature of electricity prices – which average $0.12/kWh in the U.S. and can be significantly less for commercial and industrial users, falling to almost nothing when combined with local solar generation and storage – owners can expect to gain $200,000 or more in savings over a million miles based on fuel costs alone.

Reservations for the Tesla Semi can be made for $20,000 USD per truck. Production in 2019.

Reference

Ball and DetentA simple mechanical arrangement used to hold a moving part in a temporarily fixed position relative to another part. The ball slides within a bored cylinder, against the pressure of a spring, which pushes the ball against the detent, a hole of smaller diameter than the ball. When the hole is in line with the cylinder, the ball falls partially into the hole under spring pressure, holding the parts at that position. Additional force will push the ball back into its cylinder, compressing the spring, and allowing the parts to move.

Bearing The part of a machine within which a rotating or sliding shaft is held. In some bearing types, balls or rollers are used between the bearing surfaces to reduce rolling friction.

Bell crank A pivoting double lever used to change the direction of applied motion.

Boss A cylindrical projection, as on a casting or a forging. Usually provides a contact surface around a hole.

Broach To finish the inside of a hole to a shape other than round, as in a keyway. The tool for the process, which has serrated edges and is pushed or pulled through the hole to produce the required shape.

Burnish To smooth or polish by a rolling or sliding tool under pressure.

Bushing A smooth walled bearing (AKA a plain bearing). Also, a tool guide in a jig or fixture.

Cam A mechanical device consisting of an eccentric or multiply curved wheel mounted on a rotating shaft, used to produce variable or reciprocating motion in another engaged or contacted part (cam follower). Also, Camshaft.

Casting Any object made by pouring molten metal into a mold.

Chamfer A flat surface made by cutting off the edge or corner of an object (bevel).

Clevis A U-shaped piece with holes into which a link is inserted and through which a pin or bolt is run. It is used as a fastening device which allows rotational motion.

Collar A cylindrical feature on a part fitted on a shaft used to prevent sliding (axial) movement.

Collet A cone-shaped sleeve used for holding circular or rodlike pieces in a lathe or other machine.

Core To form the hollow part of a casting, using a solid form placed in the mold The solid form used in the coring process, often made of wood, sand, or metal.

Counterbore A cylindrical flat-bottomed hole, which enlarges the diameter of an existing pilot hole. The process used to create that feature.

CountersinkA conical depression added to an existing hole to accommodate and the conic head of a fastener recessing it below the surface of a face.

Coupling A device used to connect two shafts together at their ends for the purpose of transmitting power. May be used to account for minor misalignment or for mitigating shock loads.

Die One of a pair of hardened metal plates or impressing or forming desired shape. Also, a tool for cutting external threads.

Face To machine a flat surface perpendicular to the axis of rotation of a piece.

Fillet A rounded surface filling the internal angle between two intersection surfaces. Also Rounds

Fit The class of contact between two machined surfaces, based upon their respective specified size tolerances (clearance, transitional, interference)

Fixture A device used to hold a workpiece while manufacturing operations are performed upon that workpiece.

Sheave A grooved wheel used to accommodate a belt for the transmission of power. Sometimes referred to as a pulley sheave.

Shim A thin strip of metal inserted between two surfaces to adjust for fit.

Shoulder A plane surface on a shaft, normal to the axis, produced by a change in diameter.

Spline A cylindrical pattern of keyways. May be external (L) or internal (R)

Spotface a round machine surface around a hole on a casting or forging, usually to provide a contact surface for a fastener or other mating component.

Standoffs A mounting designed to position objects a predetermined distance above or away from the surface upon which they are mounted.

Tap To cut internal machine threads in a hole, the tool used to create that feature.

Undercut A cut having inward sloping sides, to cut leaving an overhanging edge

Yoke A clamp or vise that holds a machine part in place or controls its movement or that holds two such parts together. A crosshead of relatively thick cross section, that secures two or more components so that they move together.

Turbocharger Size

Turbo selection isn’t what it used to be. Once upon a time, self-proclaimed engineers were content to build an engine that produced massive power at high rpm, but drove like a dog at anything but. However, once hot-rodders figured out that anybody could bolt a junk turbo to any engine and make power, focus shifted from top-end force to overall driveability. With a little bit of extra work, anyone with a seventh-grade education can one-up the experts of yore and pick the perfect turbo for any application.

Assess your budget. Building a turbocharged engine isn’t about just bolting a giant huffer to the exhaust manifolds and calling it a day. The turbo might only cost you $500, but a good install doesn’t stop there. Turbochargers make power as a function of the engine’s original horsepower and torque, so building an engine to make more power before bolting the turbo onto it will likely yield benefits that compensating with huge boost won’t.

Determine the required airflow in cubic feet of air per minute. Boost doesn’t make power, it just shoves more air through your engine. Because engines typically operate an air/fuel ratio of about 14 parts air to 1 part fuel, and because gasoline contains a certain amount of energy (about 114,000 British Thermal Units per gallon), you can make a direct correlation between airflow in cfm and horsepower. That ratio is about 150 cfm to 100 horsepower. As an example, let’s put together a 900 horsepower Chevrolet 350: For this application, you’ll need about 1,350 cfm of air.

Calculate your engine’s non-turbo airflow in cfm. There are three ways to do this: You can either use an online cfm-to-horsepower calculator that takes engine displacement, efficiency and rpm into account, and you can extrapolate from the engine’s stock horsepower; or you can take the engine to a dyno room and check it. For our example engine, we’ll say that (in non-turbo form) it produces 300 horsepower at 5,500 rpm, at an 80 percent volumetric efficiency. The online calculator gives us 446 cfm airflow, and using the 150-cfm/100-horsepower ratio gives us 450 cfm.

Divide your required airflow by your engine’s stock airflow to determine the required boost pressure ratio (the ratio of boost pressure to atmospheric pressure, which is about 14.7 psi). For the example engine, you arrive at a pressure ratio of exactly 3.00. Here’s a bit of trickery, though: Dividing desired horsepower by non-turbo horsepower will give you the same pressure ratio figure as going through this long-form cfm-to-horsepower-to-pressure ratio calculation. You only went this far to understand the factors that you’ll be dealing with in turbo selection from here on.

Look through a manufacturer’s selection of “turbo maps.” A turbo map is a graph that indexes airflow to pressure ratio, and gives a visual representation of turbo efficiency at a given pressure ratio and cfm. You’ll see pressure ratio on the vertical axis and the airflow on the horizontal axis. A compressor map looks something like an elongated bulls-eye: the center of that bull’s eye is the compressor’s maximum efficiency range, which is where it makes boost without producing excess heat.

Compare your engine’s required pressure ratio and airflow in cfm to various compressor maps and find one that puts your target airflow/pressure point in the center-to-upper-right-hand corner of the compressor’s maximum efficiency range (the center of the bulls-eye). Many times you’ll find airflow expressed in the metric “m3/s,” or meters cubed per second. To convert cfm to m3/s, multiply cfm by 0.00047. For our example engine, we’ll need to find a turbo that supplies full efficiency at a 3.00 pressure ratio at 0.6345 m3/s flow. Again, find a compressor where that point falls in the center-to-upper-right-hand corner of the turbo’s maximum efficiency range.

Repeat Steps 2 through 7, using the engine’s peak torque rpm. The Chevy 350 in our example makes its peak torque at 2,000 rpm, where (according to the stock dyno graph) it makes 140 horsepower. Apply the 150-cfm/100-horsepower rule and you’ll find that this engine uses 210 cfm at that rpm. Multiply that airflow by the required pressure ratio (3.00) and you have your low-end boost response requirement. In addition to producing a 3.00 pressure ratio at 1,350 cfm (0.6345 m3/s), it should produce that same 3.00 PR at 630 cfm (0.2961).

Search and search some more until you find a turbo that’s completely spooled up (producing a 3.00 PR, in this case) at your torque-peak airflow and maintains that PR through the engine’s horsepower-peak airflow. You’ll often find that, for larger engines like our 350, such turbos do not exist. No turbo out there will provide those PR and flow numbers over such a wide spectrum of airflow.

Re-calculate for a multiple-turbo setup. If you can’t find a turbo to fit, divide your airflow figures by the number of turbos you want to use. Two turbos flow twice as much air as one, and smaller turbos have a wider efficiency range relative to absolute airflow than smaller ones. So, for our example 350, divide 1,350 cfm (0.6345 m3/s) and 630 cfm (0.2961) by two; now you need a pair of turbos that will provide a 3.00 PR at 675 cfm (0.3172 m3/s) to 315 cfm (0.1480 m3/s). That’s a spread of only 360 cfm for the little twin-turbo setup, versus 720 cfm for the single, big turbo setup — a much more achievable goal for any compressor.

Tip

If you got all disappointed when you got to Step 7 and found out that you’d have to do everything over again, then find a turbo that fit both requirements, then don’t feel bad. Some of the biggest names in the business don’t bother calculating the airflow spread from peak torque to peak horsepower. However, this little oversight just isn’t cool for modern turbo-engine builders. The modern turbo engineer understands that quality turbo selection is about performance throughout the engine’s entire operating range, not just at peak horsepower. Turbo lag is so 1980s.

Warnings

When you do turbocharge your vehicle, make sure to support it with other modifications, as the turbo will probably make other parts of your car break.

It would be a good idea to install forged pistons, increase injector capacity, a higher flowing fuel pump, a new exhaust system, head studs, and forged connecting rods.

Installing a turbocharger yourself, and making it live, is a very difficult and in depth project. If you’re a beginning mechanic, it is not recommended that you try this unless you have someone experienced helping you.

The increased power of your vehicle can also make other parts of your car break. It could snap your axles, bend your drive shaft, break the rear end in a RWD car, and even bend your car from the increased torque. Be sure to upgrade the other parts of your car at the same time as you install the turbocharger, or else you could end up with a powerful car sitting in the driveway because there’s no way to put the power down.

Rotary and reciprocating compressors are both components of gas transfer systems. They both have the same purpose–to bring a gas into the system, inhale exhaust, then repeat the process. They both do this by changing the pressure at certain points in order to force gas in and exhaust out.

Pistons

One key difference is that reciprocating compressors use pistons while rotary compressors do not. A reciprocating compressor has a piston move downwards, reducing pressure in its cylinder by creating a vacuum. This difference in pressure forces the cylinder door to open and bring gas in. When the cylinder goes back up, it increases pressure, thus forcing the gas back out. The up-and-down motion is called a reciprocating motion, hence the name.

Rollers

Rotary compressors, on the other hand, use rollers. They sit slightly off-center in a shaft, with one side always touching the wall. As they move at high speeds, they accomplish the same goal as the reciprocating compressors–one part of the shaft is always at a different pressure than the other, so gas can come in at the low pressure point and exit at the high pressure point.

Advantages and Disadvantages

Reciprocating compressors are marginally more efficient than rotary compressors, generally being able to compress the same amount of gas with between 5 and 10 percent less energy input. However, since this difference is so marginal, most small-to-medium level users are best off using a rotary compressor. Reciprocating compressors are more expensive and require more maintenance, so it is often not worth the extra cost and headache for such a small difference in efficiency.

Large users, however, are generally best-served by reciprocating compressors. These are users for whom 5 percent represents a substantial figure, often substantial enough to justify the added expense.

The laws of thermodynamics dictate energy behavior, for example, how and why heat, which is a form of energy, transfers between different objects. The first law of thermodynamics is the law of conservation of energy and matter. In essence, energy can neither be created nor destroyed; it can however be transformed from one form to another. The second law states that isolated systems gravitate towards thermodynamic equilibrium, also known as a state of maximum entropy, or disorder; it also states that heat energy will flow from an area of low temperature to an area of high temperature. These laws are observed regularly every day.

Melting Ice Cube

Every day, ice needs to be maintained at a temperature below the freezing point of water to remain solid. On hot summer days, however, people often take out a tray of ice to cool beverages. In the process, they witness the first and second laws of thermodynamics. For example, someone might put an ice cube into a glass of warm lemonade and then forget to drink the beverage. An hour or two later, they will notice that the ice has melted but the temperature of the lemonade has cooled. This is because the total amount of heat in the system has remained the same, but has just gravitated towards equilibrium, where both the former ice cube (now water) and the lemonade are the same temperature. This is, of course, not a completely closed system. The lemonade will eventually become warm again, as heat from the environment is transferred to the glass and its contents.

Sweating in a Crowded Room

The human body obeys the laws of thermodynamics. Consider the experience of being in a small crowded room with lots of other people. In all likelihood, you’ll start to feel very warm and will start sweating. This is the process your body uses to cool itself off. Heat from your body is transferred to the sweat. As the sweat absorbs more and more heat, it evaporates from your body, becoming more disordered and transferring heat to the air, which heats up the air temperature of the room. Many sweating people in a crowded room, “closed system,” will quickly heat things up. This is both the first and second laws of thermodynamics in action: No heat is lost; it is merely transferred, and approaches equilibrium with maximum entropy.

Taking a Bath

Consider a situation where a person takes a very long bath. Immediately during and after filling up the bathtub, the water is very hot — as high as 120 degrees Fahrenheit. The person will then turn off the water and submerge his body into it. Initially, the water feels comfortably warm, because the water’s temperature is higher than the person’s body temperature. After some time, however, some heat from the water will have transferred to the individual, and the two temperatures will meet. After a bit more time has passed, because this is not a closed system, the bath water will cool as heat is lost to the atmosphere. The person will cool as well, but not as much, since his internal homeostatic mechanisms help keep his temperature adequately elevated.

Flipping a Light Switch

We rely on electricity to turn on our lights. Electricity is a form of energy; it is, however, a secondary source. A primary source of energy must be converted into electricity before we can flip on the lights. For example, water energy can be harnessed by building a dam to hold back the water of a large lake. If we slowly release water through a small opening in the dam, we can use the driving pressure of the water to turn a turbine. The work of the turbine can be used to generate electricity with the help of a generator. The electricity is sent to our homes via power lines. The electricity was not created out of nothing; it is the result of transforming water energy from the lake into another energy form.